Road-deposited sediment, soil and precipitation (RDS) in Bratislava, Slovakia: compositional and spatial assessment of contamination

Background, aim and scope  The urban environment in Bratislava is, in association with rapid urbanisation and industrialisation, significantly influenced by several potential sources of pollution, including automobile exhaust and industry emmissions. Urban road-deposited sediments contain many potentially toxic elements such as Pb, Cr, Cu, Zn and also Fe at concentrations much higher than in soil. In this study, the chemical composition and spatial variability of road-deposited sediments in urban area of Bratislava were assessed for the elements As, Cd, Cr, Cu, Hg, Ni, Pb, Fe and Mn. Additional evaluation of archive data for soil, snow and atmospheric dust was undertaken to provide an integrated view on urban environment contamination. Materials and methods  Urban road-deposited sediments (RDS) were collected during summer 2003 and 2004 mainly from major city crossroads. RDS samples were analysed for total metal content, pseudo-total metal content (HNO₃ digestion) and by a sequential extraction method, grain fraction composition and mineralogical composition (X-ray analysis). Metal concentrations in soil and snow samples from urban and non urban city area were compared. Results and discussion  The highest concentrations for all metals were found in the finest RDS fraction (<0.125 mm). Whilst in the fraction <1 mm mean concentrations of Cr, Cu and Pb reached 55.2, 143.8 and 34.4 mg kg⁻¹, respectively, for the fraction <0.125 mm, markedly higher contents of these elements were documented at the level of 86.8, 218.4 and 63.1 mg kg⁻¹, respectively. The soil contents of potentially toxic risk elements in the urban area including As, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn were higher than in the non-urban area (except for Cd with similar contents). This distribution pattern of evaluated chemicals in urban and non-urban area is more evident in the case of winter precipitation (snow). The snow concentrations of As, Cr, Cu, Fe, Mn, Pb and Zn in the urban area were two tot five times higher than in non-urban area. Conclusions and recommendations  Monitoring of road-deposited sediments, dust, soil and precipitation has confirmed the significant contamination of the urban environment in Bratislava with potentially toxic elements that can pose a threat for the health of its residents. Future works should be based on analyses of temporal variability of RDS and analyses of organic matter content.     

Metal speciation in acidified mountain streams in Central Sweden

The study was performed in mountain streams in Central Sweden where a dramatic decrease in fish populations has been observed during the latest years. The spring runoff caused acid surges of pH 4.4 to 5.5 and high concentrations of Fe, Mn and Al occured in the stream waters. Water samples were collected during fish cage experiments performed during spring flood of 1985. The metal fractions were separated with filtration, in-situ dialysis and ion-exchange technique and determined using atomic absorption spectroscopy. The elements analyzed included Fe, Mn, Al, Zn, Cu, Pb and Cd. During spring flood, when a 100 % fish mortality was observed, particulate forms of Fe, Al and Mn dominated and were probably responsible for the toxic action. The high leaching of Fe, Mn and Al at spring flood during the recent years is a new phenomenon and seems to be caused by the increased acid deposition to the area.     

Heavy metals in perch (Perca fluviatilis L.) from two acidified lakes in the salpausselkä esker area in Finland

Hg concentrations in muscle and Cd, Pb, Al, Zn and Fe concentrations in muscle, liver and kidney ofPerca fluviatilis from two acidified lakes in the Salpausselkä esker area in Southern Finland were studied. The metal concentrations in perch from the Tiilijärvi lakes were similar to those in other acidified Finnish lakes. Only Hg concentrations correlated strongly with the age and size of perch. The need for age correction in studies on the Hg concentrations on perch was noticed. The highest concentrations of Cd, Pb and Zn occured in kidney and those of Al and Fe in liver.     

Relationships between the atmospheric deposition of trace elements,major ions,and mercury in florida: The FAMS project (1992–1993)

A multiple chemical tracer approach was used in an effort to account for the atmospheric Hg deposition measured throughout Florida as part of the Florida Atmospheric Mercury (FAMS) Study. Samples of bulk deposition and wet-only deposition were analyzed for a suite of major ions and trace elements in addition to Hg. Significant correlations were found between three groups of elements: Al, Mn, and Fe; Ni, Cu, Zn, and Cd; and As, V, and Pb. However, Hg did not correlate strongly with any of the other chemical tracers. Annual bulk deposition fluxes are attributed to sea-salt aerosols (Na, Cl), the delivery of Saharan dust (Al and Fe), the supply of anthropogenic pollutant aerosols (V, Ni, Cu, Zn, As, Cd, Pb), acidic aerosols (nitrate and nss-sulfate), and an unidentified source for Hg.     

Changes in Concentrations of Major Elements and Trace Metals in Northeastern U.S.-Canadian Sub-Alpine Forest Floors

The forest floor at high elevation spruce-fir sites from southern Vermont, U.S. to the Gaspé Peninsula, Québec, Canada was sampled and analyzed in 1979 and re-sampled and analyzed in 1996 to study temporal changes in the impacts of atmospheric pollutants. We determined organic matter mass, pH, and concentrations of Al, Ca, Fe, K, Mg, Na, Cd, Cu, Hg, Pb, and Zn for the litter (L = fresh litter plus Oi horizon) and fermentation plus humic horizons (F+H) (= Oe plus Oa horizons) of the forest floor. There were no trends for Al or Fe concentrations in the 1979 or 1996 L along the transect. Several sites had significantly lower Al and Fe values in 1996 than in 1979, likely indicating less mineral soil in the 1996 samples. The 1996 concentrations of Ca in L increased along the transect from 0.22% dry weight (dw) in Vermont to 0.60% dw in Québec. Concentrations of Mg in L were relatively constant along the transect. Neither Ca nor Mg changed at sites from 1979 to 1996, indicating unchanged base status. Concentrations of Cd did not vary spatially along the transect but decreased at all sites from 1979 to 1996. Cu and Zn did not vary spatially or with time. In 1979, the concentration of Hg in L ranged between 150 and 300 μg kg^?1 dw, with no spatial gradient. By 1996, Hg concentrations were 25 to 50% lower in L, with decreases generally proportional to the concentration in 1979. The concentration of Pb in 1979 L decreased significantly from 200 mg kg^?1 dw in southern Vermont to 60 mg kg^?1 dw in Québec. By 1996, the Pb concentration in L ranged between 32 and 66 mg kg^?1 dw with no spatial trend along the transect. Decreases in Pb concentrations at sites were proportional to the absolute value in 1979. The concentrations of Cd, Hg, and Pb have declined in litter from 1979 to 1996, indicating a decline in atmospheric deposition. Higher Hg and Pb accumulation rates to the southwest are suggested for the past as indicated by (F+H) concentrations and inventories of Hg and Pb. The decline of Pb in L is consistent with the decreased use of leaded gasoline starting in the 1970s; the declines in Cd and Hg probably reflect lower emissions over the same period. Declining concentrations of Cd, Hg, and Pb in L parallel those documented in recent lake and peat sediments in the northeastern United States.     

Study on the elemental composition of marine particulate matter collected on different filter material

The chemical composition of marine particulate matter from the Southern Baltic has been studied using ICP atomic emission spectrometry. The samples were collected on polycarbonate 0.4 µm, cellulose acetate and glass fiber 0.45 µm filters, and on polycarbonate filters of 0.2, 0.4, 0.6, and 1.0 µum pore size. The suspensions were analyzed for the major elements Ca, Mg, Al, Fe, and P, and for the minor and trace constituents: Mn, Mo, Zn, Cu, Co, Cd, Cr, As, Se, Sb, Ag, and S. The concentrations of metals calculated on dry weight basis were higher when polycarbonate filters were used while the values for cellulose acetate and glass fiber filter were comparable. The determination of net mass particulate matter was the main reason for these differences. A comparative study of the chemical composition of suspensions from the Southern Baltic and from other areas showed a similar range of concentrations of particulate elements in coastal waters.     

Trace element distributions in soils developed in loess deposits from northern France

A pedo‐geochemical survey was carried out in the Nord‐Pas de Calais region (France) on soils developed in loess deposits. Total concentrations of Al, Fe and 18 trace elements, as well as common soil characteristics, were determined in samples from 52 surface and 97 deep horizons developed in these loess deposits. The Pb isotopic composition was determined in two sola. The composition of deep horizons, compared with that of the upper continental crust, with that of horizons developed from 21 other sedimentary rocks from the region and with that of loess from various parts of the world, confirms that loess from the Nord‐Pas de Calais region derives from multi‐recycled and well‐mixed ancient sedimentary rocks. Correlation analysis shows that least mobile (i.e. ionic potential (Z/r) is between 3 and 7) geogenic elements (Bi, Co, Cr, Cu, In, Ni, Pb, Sn, Tl, V, Zn) are associated with the fraction <2 µm (which we define as ‘lutum’). More mobile elements (As, Cd, Hg, Mn, Mo, Sb, Se) are less associated with this fraction. Cadmium is particularly linked to Mn. The distribution of [trace element]/([Al] or [Fe]) in the French loess gives the background content for soils developed from most sedimentary materials in northwestern Europe. Topsoils are enriched with all the trace elements examined, except Co, Cr and Ni. Enrichments with Cd, Cu, Mn and Zn are greater in cultivated soils than in forest soils. Enrichments with Pb and with Cu, Hg, Mo, Sb, Se and Sn are mainly due to human contamination through atmospheric fallout. Organic matter seems to act as a sink for all the exogenous trace elements.     

Heavy metal inputs to Mississippi Delta sediments

Heavy metal concentrations were determined in suspended particulates, filtered water and sediment collected in the Mississippi River and from its marine delta. More than 90% of the metal load of the river is associated with particulate matter, which is relatively constant in chemical composition with time and place. The Mississippi River suspended material is similar to average crystal rocks in Fe, Al, V, Cr, Cu, Co, Mn, and Ni concentration but is generally enriched in Zn, Cd and Pb. Sediment cores dated by the Pb 210 method show that the Cd and Pb enrichments are recent phenomenon and are most likely due to the activities of man. About 6000 tonne of Pb and 300 tonne of Cd are being added to the delta sediments by man each year, more than 30 times the amount added to the Southern California Bight. River particulate matter is essentially identical to deltaic sediments in Al, Fe, Cr, V, Cd and Pb concentration, but the sediments are depleted in Co, Cu, Mn, Ni and Zn by 20 to 40%. Chemical leaching of the solids show the metal losses to be primarily from the oxide phase, suggesting diagenetic reduction and mobilization as a mechanism. Trace metal concentrations in filtered Mississippi River water were below the limits for safe drinking water and were similar to world average river values. The abundant river suspended matter and high pH combine to keep dissolved trace metal concentrations low.     

Impact of man's activities on the chemical composition in the sediments of Lakes Ontario,Erie and Huron

The concentrations of organic matter, major elements and trace elements were determined at 14 core locations in Lakes Ontario, Erie and Huron. The chemical composition of the cores was related to the sediment particle size, Eh, pH, chronology and location of sampling site. Concentrations of Si, Al, Fe, Mg, Ti, K and Na, which represent the major mineral species in the sediments, are generally uniform in each core. Surface enrichments of Hg, Pb, Zn, Cd, Cu, Be, V, Org-C, N and P are observed at most locations, with their concentrations, usually much greater above the Ambrosia horizon (≈ 120 yr BP), irrespective of the depth of the horizon. The enrichment of these elements is attributed to anthropogenic inputs in recent years. Concentration profiles for Mn and S are related to the migration of these elements in the pore waters. Anthropogenic loadings of the trace metals and nutrients parallel the population and degree of industrialization of each lake drainage basin. Natural loadings parallel the sedimentation rates. Although it is not possible to evaluate the contributions of the trace metals from various sources, evidence is presented that atmospheric inputs are important.     

Verbesserung der Chrombestimmung in Königswasseraufschlüssen von Bodenproben mit der Atomabsorptions-Spektroskopie (Flammen-Technik)

The improvement of Chromium determination in soil extracts by means of atomic absorption spectroscopy (flame technique) In order to achieve an improvement in the determination of chromium in soil extracts by means of atomic absorption spectroscopy, the influence of elements (Hg, Cd, Pb, Cu, Ni, Zn, Fe, Al, Mg, K, Na, Ca, P) which could possibly disturb the measurements of the chromium absorption using different flames (air/acetylene and laughing gas/acetylene), flame characteristics and measuring wavelengths (357,9 nm and 359,4 nm) was investigated. In this connection disturbances occurred which both raised or lowered the signal level. For nearly interference-free determination of chromium in the field of soil analysis we recommend the measuring wavelength 359,4 nm and the blue air/acetylene flame which has a low fuel gas content or the laughing gas/acetylene flame (approx. 5 cm high inner reduction zone).     

Trace metal concentrations in borehole waters from the Upper Regions and the Accra Plains of Ghana

The concentrations of Hg, Cu, Pb, Zn, Cd, Fe, Mn, Cr and As were measured in groundwaters from the Upper West and Upper East Regions and the Accra Plains of Ghana. Apart from Fe, the trace metal levels for the two Upper Regions were similar. Samples from the Accra Plains had the highest trace metal concentration. However, Hg and As were undetected in all the samples. While the mean Cd, Mn and Cu concentrations for all the 3 study areas fell below the WHO limit, values for Pb and Cr exceeded the WHO limits for drinking water. Iron exceeded the limits in the Upper West Region and the Accra Plains. Overall, the most abundant elements in groundwaters were Zn, Fe and Cr.     

Assessment of Fe,Zn, Cd,Hg, and Pb in the Jordan and Yarmouk River Sediments in Relation to Their Physicochemical Properties and Sequential Extraction Characterization

Forty-six surface sediment samples taken along the beds of boththe Jordan and Yarmouk Rivers were analysed for Pb, Cd, Zn, Fe andHg by atomic absorption spectrophotometer. Extraction techniqueswere used to establish the association of the total concentrations of Pb, Cd, Zn and Fe in the sediment samples withtheir contents in the exchangeable, carbonate, Fe/Mn oxides, organic and residual fractions.In the sediments of the Jordan River the recorded heavy metalsconcentrations were as follow: 8.1 ppm for Pb, 0.63 ppm for Cd, 20.3 ppm for Zn, 6 ppm for Hg and 1265.6 ppm for Fe; whereas in the sediment of Yarmouk River were 8.4 ppm for Pb, 0.67 ppm for Cd, 26.4 ppm for Zn, 6.2 ppm for Hg and 1370 ppmfor Fe. Pb, Cd, Zn, and Fe concentrations in the sediments ofboth rivers reflect the natural background value in shale, whereas Hg is moderately enriched. I-geo (geo-accumulation index) of metals in the sediments under study indicates thatthey are uncontaminated with Pb, Zn and Fe; contaminated tomoderately contaminated with Cd; and strongly contaminated with Hg. Heavy metal content in the sediments were found to be significantly influenced by different physico-chemical parameters. The effect of these physico-chemical parameters canbe arranged in the following order: clay fraction > organicmatter fractions > carbonate fraction > silt fraction. As sequential extraction procedure shows that the total concentration of the heavy metals are largely bound to the residual phase (retained 79.5% of Pb, 38% of Cd, 54.4% of Zn and 51.6% of Fe in Jordan River Sediments; and 88.6% of Pb, 48.2% of Cd, 37.6% of Zn and 59.5% of Fe in the YarmoukRiver sediments). The following sequence of mobility are suggested: Fe > Cd > Zn > Pb in Jordan River sediments, and Fe > Zn > Cd > Pb. in Yarmouk River sediments.     

Observations on metal concentrations in three species of shark (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstoni) from southeastern Australian waters

Deep sea dog sharks (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstonii) were captured from the waters off western Victoria, Australia, in April and May 1998. The elements As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, Sr, and Zn were detected in the muscle tissue. The concentrations of Al, Ba, Be, Cr, Mo, Ni, Pb, and V were below the detection limits of the instrumental techniques employed (ICP-ES and GF-AAS). However, significant concentration differences between species were detected for As, Cd, Hg, and Zn. C. owstoni contained the highest concentrations of each of these elements. The concentrations of Cu, Pb, and Zn in each species were below the maximum levels permitted in food by the Australian Food Standards Code. The maximum permitted concentrations of As and Hg were exceeded in all species, and weekly consumption of 400 g of any of these sharks would result in intake of more than the FAO's provisional tolerable weekly intake. Although C. crepidator and D. calcea have strong relationships between length and mercury concentration, C. owstoni does not. Placing C. crepidator and C. owstoni in the same genus, therefore, is worth re-examination as the mechanisms for controlling mercury in C. owstoni appear to differ from that used by both C. crepidator and D. calcea.     

Vergleich zwischen Total- und königswasserextrahierbaren Elementgehalten in natürlichen Böden und Sedimenten

Comparison between total- and aqua regia extractable contents of elements in natural soils and sediments Total- and aqua regia extractable contents of 19 elements from 28 soil samples with widely varying composition of the ISE ring analytical program (INTERNATIONAL SOIL-ANALYTICAL EXCHANGE) of the year 1995 to 1997 have been taken to find out the comparability between the two fractions. The relations between the two fractions and pH, organic matter and clay content were considered by means of single and multiple regressions. The correlations between the total and aqua regia extractable contents of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, P, Pb and Zn are very close, whereas Al, Ba, K, Na and Sr are not or only weakly correlating. The multiple regressions show that the content of some aqua regia extractable elements and the proportion (in %) of the total contents is correlated with pH, organic matter and/or content of clay. In the same way the proportion of aqua regia extractable elements is closely related (except Fe and Hg) to the soil pH. Hereby the proportion of the aqua regia extractable content increases with increasing pH in the range 3,5—7,7. The determined equations are tested for As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn by using the values of certified reference material. The estimated aqua regia extractable contents are being compared with values of reference material. The average proportion of the calculated to the measured aqua regia contents of an element in percent are 99 for Zn, 98 for Co, Cu and Mn, 94 for Cd, 90 for Ni, 88 for Cr, 105 for Hg, 113 for As and 114 for Pb.     

Variations in plant and soil lead and mercury content in a major Honolulu Park, 1972 to 1987, a period of significant source reduction

The Ala Manna beach and park area in SE Honolulu is exposed to (1) local automotive exhaust emissions from the heavily travelled boulevard and high density shopping mall located immediately to the north; (2) a frequently congested access road located between the park proper and the beach; and (3) a remote source of geothermal and volcanic emissions 400 km to the SE on the Island of Hawaii. Between 1972 and 1987 both local Pb emissions and the more remote Hg emissions fell by more than 80%. Reductions in Pb reflected declining use of ‘leaded’ gasoline; reductions in Hg reflected a declining output of Hg⁰ vapor from volcanic and fumarolic sources. We compared Pb and Hg contents along a 150 m transect of soil and the grass Cynodon in 1972 and 1987. At the boulevard median divider, where particulate Pb deposition is heaviest, the metal content of the upper 5 to 6 cm of soil was reduced by approximately 53% but in the main body of the park no consistent pattern was found and an overall 21% reduction was observed. The highest soil Pb values were measured at the boulevard and beach access roads, with lower intermediate levels. The grass shoots showed a similar pattern but overall Pb content fell 65% between 1972 and 1979, a value more consistent with the reduction in Pb contamination from leaded gasoline. Neither soil nor plant Hg contents reflect a strong roadside to interior concentration gradient, but both fell between 1972 and 1987 by 60 and 68%, respectively. The biogeochemical significance of concentration ratios (plant/soil) and Pb/Hg atomic ratios was examined. With the exception of soil fixation of Pb in a relatively non-mobile soluble form, we conclude that for the two metals, the changes in levels reflect changes in the source (local for Pb and remote for Hg). There is also evidence for physiological regulation in the uptake of the two elements.     

Mercury speciation in Lake Baikal

Research on mercury (Hg) distribution and speciation was carried out in Lake Baikal, a large, strong-oligotrophic freshwater reservoir in Siberia, Russia, during June 1992 and march 1993. In summer, total Hg in the water column ranged from 0.14 to 0.77 ng Hg/L, with the highest concentrations observed in the central basin of the lake in surface water samples. Labile inorganic Hg was found to be 7 to 20 % of the total Hg content. Highest total Hg concentrations were found in river waters: up to 2 ng Hg/L. Labile methylmercury (MeHg) concentrations ranged from 2 to 38 pg Hg/L in the water column, with the higher concentrations in the central part of the lake, and showing a slight increase in near bottom waters. Labile MeHg makes up 1 to 15 % of the total Hg content in the water column, with larger fractions in deep waters. The slight increase of the MeHg gradient with depth corresponds with the O₂ minimum region. Highest MeHg concentrations were observed in river waters (up to 145 pg Hg/L) and in some bays of the lake (up to 160 pg Hg/L). In these high temperature- and phytoplankton-rich water masses, the MeHg-fraction increased up to 35 % of total Hg. Labile MeHg concentrations in water samples taken in winter in the southern basin (under the ice cover), showed slightly higher concentrations than in summer, possibly due to an early spring bloom. In rainwater, total Hg ranged from 3 to 20 ng Hg/L and MeHg from 0.1 to 0.25 ng Hg/L. In snow, a large fraction of total Hg is bound to particulate matter; concentrations of total Hg ranged from 8 to 60 ng Hg/L and labile MeHg from 0.1 to 0.25 ng Hg/L. Atmospheric Hg was found to be 0.73 to 2.31 ng/m³ as gaseous Hg and 0.005 to 0.02 ng/m³ in its particulate form. Spatial distribution patterns of atmospheric Hg show slightly higher concentrations over the central part of the lake and the Selenga river delta. In winter, atmospheric Hg values (measured in the southern region), ranged from 1.2 to 6.1 ng/m³ as total gaseous Hg and 0.02 to 0.09 ng/m³ as total particulate Hg, and are higher than in summer, probably influenced by coal burning and traffic by the local population. MeHg contents in fish ranged from 20 ng Hg/g dry weight in small Cottocomephorus to 300 ng Hg/g dry weight in pike and trout species, which were caught in organic-rich waters.     

Impact of a ski basin on a mountain watershed

The input of heavy metals by automobile exhaust pollution associated with the ski basin activities is the primary concern of this paper. Stream, snowpack and lichen samples were collected and analyzed for Pb, Zn, and Cu. Some lichen samples were also analyzed for Ca, Mg, Na, K, Fe, and Mn, as well as Pb, Zn, and Cu. Snowpack samples from roadside areas demonstrated increased levels of Pb and Cu in comparison to areas up to 180 m from the road, but heavy metal levels at more remote areas were comparable to roadside levels. In all snow samples the heavy metals associated with the particulate matter was the major form of all inputs. Heavy metals in streams were also highly correlated with the particulate matter content. Heavy metal inputs to the watershed were greater than stream export, indicating an accumulation of heavy metals by the system. The forest canopy appears to be the major factor in the accumulation of heavy metals, probably due to better interception and impaction of the particulate matter by the canopy.     

Metal content of Sphagnum mosses from two Northern Canadian bog ecosystems

Samples of Sphagnum moss were collected from Kinoje Lake, northern Ontario, and Porter Lake, Northwest Territories (N.W.T.), Canada. The samples were analyzed for the elements Cd, Ca, Cr, Cu, Fe, Pb, Mg, Mn, Hg and Zn. On a dry-weight basis, Ca was highest in concentration followed by Mg, Fe and Mn. The other elements were an order of magnitude or more lower in concentration. In general, concentrations were similar to those reported in the literature from Scandinavia. The two Canadian sites were similar in elemental composition except that the Ontario site was higher in Cd and Pb, while the N.W.T. site was higher in Mg and Hg. These differences could be due to a combination of regional geochemical and human activity differences.     

Enhancing the Reliability of Laboratory Phosphorus Filter Tests: Effect of Influent Properties and Interpretation of Effluent Parameters

The distribution of selected elements in individual fractions of organic matter from anthropogenically contaminated soils was investigated. The attention was paid especially at Hg. Furthermore, contents of S, Mg, Mn, Fe, Cu, Zn and Pb were also measured. The decomposition of organic matter to particular fractions was carried out by the resin DAX-8. Ten soil samples were collected, and the Advanced Mercury Analyzer (AMA-254) was used for the determination of the total Hg content. The two highest Hg values reached up to the concentration 10.5 mg kg^?1, and in the highest one, it was almost 29 mg kg^?1. In each extract, mercury was measured by inductively coupled plasma mass spectrometry (ICP-MS), for other elements, inductively coupled plasma optical emission spectrometry (ICP-OES) was applied. Results of the analysis show that the Hg content bound to the humic acids is inversely proportional to the content of Mg, Mn, Fe and Cu. However, this dependence was not confirmed by the samples with the mercury content above 10 mg kg^?1. In the case of fulvic acids, the relationship between Hg and S was observed and has again an inverse character.     

Variation in the geochemistry of recent lake sediments along a west east pollution gradient in the Bergen area, Norway

Twenty nine lakes were sampled on a 62 km long west-east transect near Bergen, Norway from Sotra in the west to Norheimsund in the east. Top and bottom samples of 29 sediment cores, 20–40 cm long, were collected and 17 chemical elements were measured. Sphaeroidal carbonaceous particles from fossil fuel origin were counted in the surface sediments. The study was designed to answer two questions: (1) Does lake-sediment composition reflect variations in local atmospheric pollution? (2) What factors explain the observed variation in concentration of chemical elements along this transect? Ca, Cr, Mg, and Ni concentrations along the transect appear to result from differences in the content of these elements in bedrock. Hg, Pb, and Zn concentrations in the top sediments are dominated by input from anthropogenic sources. Variation of Cd, Fe, and Zn in the top sediments seems to be dependent on variation in lake-water pH. Hg and Zn from anthropogenic sources probably result from long-transported pollution. Pb and carbonaceous particles from anthropogenic sources possibly have a local origin.